Protective gas masks or face masks are well known in the art. These masks provide breathing capabilities while protecting the mask user from noxious gases, smoke, paint fumes, etc. However, people wearing the masks often have a need to communicate with one another, particularly during emergency situations. Accordingly, several voice transmission or communication systems have been developed for this purpose.
For example, Lewis U.S. Pat. No. 3,180,333, discloses a gas mask communication system including a generally U-shaped holder connected to the mask. Preferably, the holder includes the amplification speaker in one end portion and the batteries for operating the speaker system in another end portion. The batteries and amplification system are connected in circuit with a microphone inside the mask adjacent the user's mouth. Additional or parallel speakers can be plugged into the Lewis mask communication system including, for example, a speaker attached to the belt of the wearer.
Noetzel, U.S. Pat. No. 4,980,926; Ingalls U.S. Pat. No. 4,508,936; Lewis, U.S. Pat. No. 3,180,333; Bloom U.S. Pat. No. 2,953,129; and Duncan U.S. Pat. No. 2,950,360 disclose face mask communication systems having a microphone carried in the face mask and an amplifier or speaker connected to the microphone by a cord. The amplifier or speaker is supported elsewhere, such as around the waist of the user. Such communication systems having a remote amplifier and speaker are particularly useful where the mask is a half-piece mask and does not have the ability to support the relatively heavy and bulky amplifier and speaker assembly.
The above-identified voice transmission and communication systems however, can have certain disadvantages. In particular, during installation (or removal and/or replacement) of some of these systems, certain components of the communication system, and in particular the microphone and related electronics, penetrates and structurally alters the mask in order to reproduce the user's voice. For example, Lewis shows a threaded portion for the microphone which extends through an aperture formed in the mask. However, penetrating and altering the mask can raise safety issues, can require additional assembly, and can make it difficult to remove and/or replace the voice transmission system, particularly during emergency situations.
Other systems have been developed which do not penetrate the mask. For example, Ingalls in one embodiment shows a vibration pickup located within a receptacle adhesively secured to the surface of the face mask to receive, amplify, and externally transmit vibrations received through the mask. In another embodiment, Ingalls shows a microphone located within the mask which is acoustically coupled to the pick-up assembly on the exterior of the mask. Noetzel shows a similar design using phototransmission coupling. However, these systems require additional components which are bonded (e.g., adhesively) to the exterior and/or interior surfaces of the mask. Further, in Noetzel and in the one embodiment of Ingalls, these systems require the microphone to be located within the face mask, which makes it difficult to remove and/or replace the microphone during use.